S13 SR20DET idle problems on cold start

[zboost]

My S13 which is red top SR20DET has idle problems.
It just started happening shortly after I swapped my FGK Legalis R turbo back for a HKS Hi power system.
I am unsure if this is related to the idle problem but is it possible because I didn't use a gasket from the downpipe to the cat delete pipe?

When I start her up in the morning idle fluctuates and has random surges where it drops to the point where it's about to stall and then raises back up or actually

stalls.
This continues to happen until the cars fully warmed up.
While driving as I come to a stop the car tries to stall and does unless I give it throttle as I brake.

Checked the spark plugs which are HKS branded, the tops were completely black (done around 15,000-20,000km since changed). I swapped them out for the previous HKS

spark plugs that were in, as they were atleast better than what was currently in there until I'm able to get new ones.

Injector/s are clicking, not sure if this is related to the idle problem.

Looked for vacuum leaks, couldn't find any but I might not have looked properly. If it shows hitting full boost on the boost gauge does that mean no leaks?
The genuine HKS bov appears to be leaking boost as you can hear it before it even hits +vac on the boost gauge, this has been happening long before the idle problem.

Ran new silicone vacuums for the boost controller & wastegate

Just had a new Exedy 5 puk clutch put in around 2000kms ago
Car was serviced 5,500kms ago

Engine mods:
HKS Super Fire Racing plugs
Factory injectors & coil packs
HKS Hi Power exhaust system
Cat Delete
HKS wastegate actuator
HKS SSQV Bov
GReddy Profec B Electronic Boost Controller - 8.5psi low & 14psi high
K&N Panel filter
Exedy 5 Puk Heavy Duty clutch

[zboost]

Any help please?

[KiLLeR2001]

Coming to a stop and stalling sounds like you are running atmospheric BOV without the ECU being tuned for it. Try recirculating.

Sounds like vacuum leaks to me.

[zboost]

Forgot to add the car is running very rich and using a lot more fuel ever since i upgraded from my 2.7" FGK exhaust system to my 3.3" HKS Hi-power.
With my FGK I wasn't using the cat sensor as there was no sensor port on the cat delete pipe that was used with that exhaust system. When I got the HKS one I bought another cat delete pipe with a sensor port so I ended up putting the cat sensor in.

Today I just removed the cat sensor and blocked off the port on cat delete, cleaned throttle body & IACV.

About to take it for a drive soon to see the difference but it still stalls while idling.

Was thinking it was the BOV but it was fine before so I'm unsure why it is causing issues now? Using stock ECU and tune.

[zboost]

No luck fixing :/ gonna try get my front mount setup complete and buy a new bov see if it fixes.

[ZenkiDeven19]

Sounds like you may need to possibly do a tune? Seeing as your running super rich, unless your MAF is flipping shit.

Sent from my SM-N900V using Tapatalk

[zboost]

Idle and stalling issue is finally fixed! Took the HKS bov out just blanked it off as I don't have all the parts to put the stock bov back in atm. Called the shop up it was purchased from and they asked to bring the car in so they can diagnose it and talk about refund options etc. Probably gonna switch to a GReddy bov anyway as I found one that comes with a front mount interooler piping setup I'm wanting to purchase.

Haven't driven it far yet but still appears to run rich. Unsure why the spark plugs went black so quick, is it because of it running rich or because I'm pushing too much boost without all the supporting modifications?

Not many faults left with the car besides the injector ticking and the powersteering pump was whining along with loose belt. Anyone able to help me with these?